Carrier-current system



Aug. 14, 1928. 1,680,759

' E. AUSTIN CARRIER CURRENT SYS TEM Filed May 2, 1925 SECTION A 550 7/0 5 RECEIVER yawn/rm? k (RECEIVER vvv" Allll TEA/(8) 077! I I DIAL DEV/CE DIAL DE W66 Inventor: Edwar d A ustin,

by His Attorney.

Patented Aug. 14, 1928.

UNITED STATES.

PATENT OFFICE.

EDWARD AUSTIN, OF SCHENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

CARRIER-CURRENT SYSTEM.

Application filed la a,

The present invention relates to a carrier current system of communication and more particularly to an arrangement for establishing communication between remote points of a system of distribution. v

In the o ration of direct current railway systems w ich are supplied from one or more substations, it frequently happens that the sub-stations, although distribution centers, are not necessarily communication centers from the operating point of view. For example," communication usuall centers "about an operator in the main 0 cc which is located atv the end of a feeder or trolley.

Stations which may be involved in a communication system will be located on various points on the system. To establish communication between a distant station and the main ofiice would require a large amount of ener to be impressed upon t e system at the istant station. This may in some cases be impractical since both power and space are usually at a premium, at such points.

It is the object of my invention to provide a systemof carrier communication between a remote station and any other station on a s stem of distribution which will perwit 0 a reduction in the amount of power required at the remote station, and further 80 increase the reliability of the communication.

system under adverse line conditions.

The novel features which I believe to be characteristic of my invention are set forth with particularity in the appended claims. 85 My invention, however, both as to its oranization and its method of operation will st be understood b reference to the following description ta en in connection with the accompanying drawing in which the figare represents diagrammatically a circuit organization where y my invention maybe carried into effect.

In the figure I have shown a single line 1 which may be considered as a power line or any type of electrical circuit. At remote stations C and D I have indicated receivers 2 which are responsive to a frequency F and transmitters 3-which will impress on the line a frequency F. Each, receiver and e0 transmitter is shown connected to the line through capacities which may be the form of fixed condensers or couplingv wires as desired. Associated with each transmitter is a dialing or device t similar to 1925. Serial No. 27,804.

that used in connection with automatic tele phone systems.

A main or relay station which I have designated 5 comprises areceiver 6 which operates on a frequency F and a transmitter 7 which supplies a frequency F to the line. The difference between the two frequencies will be determined somewhat by the limit of audibility, but more particularly by the design of the ap aratus used. The receiver 6 is con led to t 0 power line 1 through a tuning evice 8.

The transmitter 7 is coupled to the output circuit through'a parallel tuned circuit or trap 9. The purpose of this circuit is to suppress the received signals and thereby to increase the efliciency of the receiving circuit. The trap is not absolutely necessary for the successful 0 eration of the system and might be omit if desired. The output circuit of the main or relay receiver 6 and the main or relay transmitter 7 arecou led throu h an audio transformer indicate at 10 an also through a selective ringing relay arrangement 11 for starting or ringing purposes. z

In the operation of the device if station C wishes to call station D transmitter 3 is started by lifting the earphones from the usual hook associated with the transmitter 3.

A continuous unmodulated im ulse'is then sent out from transmitter 3. T when received by receiver 6 operates a relay to close contacts in the selective ringing relay arrangement 11. The closing of the latter contacts energizes relay transmitter 7 and causes the latter to send out a carrier wave as long as the book of transmitter 3 is not held down. When the dial device 4 is operated the transmitted carrier wave is momentarily interrupted in accordance with code combinations. These impulses or cessations cause a corresponding change in the relay in the selective ringin arrangement 11 and accordingly control t e output of transmitter 7. The impulses sent out on section B select the proper relay at some distant station and that station is called. When dialing is comleted the dial'returns to normal position ut transmitters 3 and 7 both remain operative. Modulation at 3 is then received at receiver 6 and transferred through the audio frequency transformer 10 to the modulation equipment of transmitter 7 and tranflm t ed his impulse relay in the selective ringin from the latter to section B of the system. When the receiver is replaced on the hook of the transmitter 3 it automatically sto 5 operation of transmitter 7 by releasing t e arrangement 11. When two stations are in on the line conversation may be carried on in the usual manner since each remote transmitter may control the out ut of the relay station.

Various mo ifications of the arrangement shown will readily suggest themselves to per sons skilled in the art without departing from the scope of my invention as set forth in the appended claims.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. In a system for carrier current communication or the like, a plurality of remote stations, a transmitter at each station for supplying a. certain frequency to the system, a receiver at each station responsive to another frequency, a main receiver connected to the system at a point between said stations and which is responsive to the frequency of said transmitters, a main transmitter connected to the system at a point between said stations to supply to the remote receivers said other frequency, a plurality of connections between said main receiver and said main transmitter whereby the operation of said main transmitter may be controlled from any remote station, one of said connections including a selective ringing circuit, and means at each remote station for initiating the operation of the main transmitter and controlling the ringing circuit.

2. In a system for carrier current communication or the like, a power line, a relay station comprising a receiver connected to the line and responsive to an electromotive force of a certain frequency and a transmitter connected to said receiver and arranged to impress an electromotive force of a different frequency upon the line, a plurality of remote stations connected to the relay station, a transmitter at each remote station for operating the receiver at the relay station, a receiver at each remote station responsive to the frequenc of the transmitter at the relay station an means associated with each remote transmitter for starting and controlling the operation of the main transmitter and for selectively calling any other station.

3. In a system for carrier current communication or the like, a plurality of remote stations. a transmitter at each station for supplying a certain frequency to the system, a receiver at each station responsive to another frequency, a main receiver connected to the system at a point between said stations and which is responsive to the frequency of said transmitters, a main transmitter connected to the system at a point between said stations to supply to the remote receivers said other frequency, a connection between the output circuit of said main receiver and said main transmitter whereby currents produced b said main transmitter may be modulated li y a remote transmitter, a selective ringing circuit connecting the output circuit of said main receiver and said-main transmitter, and means associated with each remote transmitter for controlling the output currents from said main transmitter.

4. In a system for carrier current communication or the like, a plurality of remote stations, a transmitter at each station for supplying a certain frequency to the system, a receiver at each station responsive to another frequency, a main receiver connected to the system at a point between said stations and which is responsive to the frequency of said transmitters, a main transmitter connected to the system at a point between said stations to supply to the remote receivers said other frequency, aconnection between said main receiver and said main transmitter whereby operation of said main transmitter may be controlled by a remote transmitter, a. selective ringing circuit connecting said main receiver and said main transmitter, and means associated with each remote transmitter for supplying an unmodulated impulse to the main receiver to thereby initiate the operation of the main transmitter, and additional means at each remote station for controlling the'ringing circuit to selectively call any other station.

In witness whereof, I have hereunto set my hand this 1st day of May, 1925.

EDWARD AUSTIN. 

